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Kusumi A, Fujiwara TK, Tsunoyama TA, Kasai RS, Liu AA, Hirosawa KM, Kinoshita M, Matsumori N, Komura N, Ando H, Suzuki KGN. Defining raft domains in the plasma membrane. Traffic 2021; 21:106-137. [PMID: 31760668 DOI: 10.1111/tra.12718] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 11/19/2019] [Accepted: 11/20/2019] [Indexed: 01/03/2023]
Abstract
Many plasma membrane (PM) functions depend on the cholesterol concentration in the PM in strikingly nonlinear, cooperative ways: fully functional in the presence of physiological cholesterol levels (35~45 mol%), and nonfunctional below 25 mol% cholesterol; namely, still in the presence of high concentrations of cholesterol. This suggests the involvement of cholesterol-based complexes/domains formed cooperatively. In this review, by examining the results obtained by using fluorescent lipid analogs and avoiding the trap of circular logic, often found in the raft literature, we point out the fundamental similarities of liquid-ordered (Lo)-phase domains in giant unilamellar vesicles, Lo-phase-like domains formed at lower temperatures in giant PM vesicles, and detergent-resistant membranes: these domains are formed by cooperative interactions of cholesterol, saturated acyl chains, and unsaturated acyl chains, in the presence of >25 mol% cholesterol. The literature contains evidence, indicating that the domains formed by the same basic cooperative molecular interactions exist and play essential roles in signal transduction in the PM. Therefore, as a working definition, we propose that raft domains in the PM are liquid-like molecular complexes/domains formed by cooperative interactions of cholesterol with saturated acyl chains as well as unsaturated acyl chains, due to saturated acyl chains' weak multiple accommodating interactions with cholesterol and cholesterol's low miscibility with unsaturated acyl chains and TM proteins. Molecules move within raft domains and exchange with those in the bulk PM. We provide a logically established collection of fluorescent lipid probes that preferentially partition into raft and non-raft domains, as defined here, in the PM.
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Affiliation(s)
- Akihiro Kusumi
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Okinawa, Japan.,Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, Japan
| | - Takahiro K Fujiwara
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, Japan
| | - Taka A Tsunoyama
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Okinawa, Japan
| | - Rinshi S Kasai
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - An-An Liu
- Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Center for Analytical Sciences, College of Chemistry, Nankai University, Tianjin, P. R. China
| | - Koichiro M Hirosawa
- Center for Highly Advanced Integration of Nano and Life Sciences (G-CHAIN), Gifu University, Gifu, Japan
| | - Masanao Kinoshita
- Department of Chemistry, Faculty of Science, Kyushu University, Fukuoka, Japan
| | - Nobuaki Matsumori
- Department of Chemistry, Faculty of Science, Kyushu University, Fukuoka, Japan
| | - Naoko Komura
- Center for Highly Advanced Integration of Nano and Life Sciences (G-CHAIN), Gifu University, Gifu, Japan
| | - Hiromune Ando
- Center for Highly Advanced Integration of Nano and Life Sciences (G-CHAIN), Gifu University, Gifu, Japan
| | - Kenichi G N Suzuki
- Center for Highly Advanced Integration of Nano and Life Sciences (G-CHAIN), Gifu University, Gifu, Japan
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Structural Domains of the Herpes Simplex Type 1 gD Protein that Restrict HIV-1 Particle Infectivity. J Virol 2021; 95:JVI.02355-20. [PMID: 33536165 PMCID: PMC8103709 DOI: 10.1128/jvi.02355-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previously, we showed that the presence of the herpes simplex virus type 1 (HSV-1) gD glycoprotein but not gB potently restricted HIV-1 particle infectivity. This restriction was characterized by incorporation of HSV-1 gD and the exclusion of the HIV-1 gp120/gp41 from budding virus particles. To determine the structural domains involved in gD restriction of HIV-1, a series of deletion mutants and chimeric proteins between gD and the non-restrictive gB were generated. Our results show that deletion of the cytoplasmic tail domain (CTD) of gD or that replacement of the transmembrane domain (TMD) with the TMD from gB slightly reduced restriction activity. However, replacement of the gD CTD with that of gB resulted in lower cell surface expression, significantly less incorporation into HIV-1 particles, and inefficient restriction of the release of infectious HIV-1. Analysis of gB/gD chimeric proteins revealed that removal of the gB CTD or replacement with gD CTD resulted in enhanced surface expression and an increase in restriction activity. Finally, we show that expression of gD without other HSV-1 proteins resulted in gD fractionation into detergent resistant membranes (DRM) and that gD co-localized with the raft marker GM1, which may partially explain its incorporation into budding virus particles. Taken together, our results suggest that expression of gD at the cell surface is likely a major factor but that other intrinsic properties are also involved in the gD-mediated restriction of HIV-1 particle infectivity.IMPORTANCE Previously, we showed that unlike the HSV-1, the presence of the gD glycoprotein in virus producer cells but not gB potently restricted HIV-1 particle infectivity. To better understand the relationship between cell surface expression, virus incorporation and restriction of HIV-1, we analyzed a series of deletion mutants and chimeric proteins in which domains of gD and gB were swapped. Our results indicate that: a) gD/gB chimeras having the cytoplasmic domain (CTD) of gB significantly reduced cell surface expression, release from cells, incorporation into virus, and reduced HIV-1 restriction; b) removal of the gB CTD or replacement with the gD CTD resulted in better surface expression, incorporation into HIV-1, and enhanced restriction; and c) the transmembrane domain of gB can influence transport and ultimately effect incorporation of gB into HIV-1. Overall, these data support a role for gD surface expression as crucial to restriction of infectious HIV-1 release.
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Detergent Resistant Membrane Domains in Broccoli Plasma Membrane Associated to the Response to Salinity Stress. Int J Mol Sci 2020; 21:ijms21207694. [PMID: 33080920 PMCID: PMC7588934 DOI: 10.3390/ijms21207694] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 10/13/2020] [Indexed: 01/09/2023] Open
Abstract
Detergent-resistant membranes (DRMs) microdomains, or “raft lipids”, are key components of the plasma membrane (PM), being involved in membrane trafficking, signal transduction, cell wall metabolism or endocytosis. Proteins imbibed in these domains play important roles in these cellular functions, but there are few studies concerning DRMs under abiotic stress. In this work, we determine DRMs from the PM of broccoli roots, the lipid and protein content, the vesicles structure, their water osmotic permeability and a proteomic characterization focused mainly in aquaporin isoforms under salinity (80 mM NaCl). Based on biochemical lipid composition, higher fatty acid saturation and enriched sterol content under stress resulted in membranes, which decreased osmotic water permeability with regard to other PM vesicles, but this permeability was maintained under control and saline conditions; this maintenance may be related to a lower amount of total PIP1 and PIP2. Selective aquaporin isoforms related to the stress response such as PIP1;2 and PIP2;7 were found in DRMs and this protein partitioning may act as a mechanism to regulate aquaporins involved in the response to salt stress. Other proteins related to protein synthesis, metabolism and energy were identified in DRMs independently of the treatment, indicating their preference to organize in DMRs.
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Yang J, Zhan XZ, Malola J, Li ZY, Pawar JS, Zhang HT, Zha ZG. The multiple roles of Thy-1 in cell differentiation and regeneration. Differentiation 2020; 113:38-48. [PMID: 32403041 DOI: 10.1016/j.diff.2020.03.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 03/17/2020] [Accepted: 03/22/2020] [Indexed: 11/17/2022]
Abstract
Thy-1 is a 25-37 kDa glycophosphatidylinositol (GPI)-anchored cell surface protein that was discovered more than 50 years ago. Recent findings have suggested that Thy-1 is expressed on thymocytes, mesenchymal stem cells (MSCs), cancer stem cells, hematopoietic stem cells, fibroblasts, myofibroblasts, endothelial cells, neuronal smooth muscle cells, and pan T cells. Thy-1 plays vital roles in cell migration, adhesion, differentiation, transdifferentiation, apoptosis, mechanotransduction, and cell division, which in turn are involved in tumor development, pulmonary fibrosis, neurite outgrowth, and T cell activation. Studies have increasingly indicated a significant role of Thy-1 in cell differentiation and regeneration. However, despite recent research, many questions remain regarding the roles of Thy-1 in cell differentiation and regeneration. This review aimed to summarize the roles of Thy-1 in cell differentiation and regeneration. Furthermore, since Thy-1 is an outer leaflet membrane protein anchored by GPI, we attempted to address how Thy-1 regulates intracellular pathways through cis and trans signals. Due to the complexity and mystery surrounding the issue, we also summarized the Thy-1-related pathways in different biological processes, and this might provide novel insights in the field of cell differentiation and regeneration.
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Affiliation(s)
- Jie Yang
- Institute of Orthopedic Diseases and Department of Bone and Joint Surgery, the First Affiliated Hospital, Jinan University, Guangzhou, 510630, Guangdong, China
| | - Xiao-Zhen Zhan
- Department of Stomatology, the First Affiliated Hospital, Jinan University, Guangzhou, 510630, Guangdong, China
| | - Jonathan Malola
- College of Pharmacy, Purdue University, West Lafayette, 47906, IN, USA
| | - Zhen-Yan Li
- Institute of Orthopedic Diseases and Department of Bone and Joint Surgery, the First Affiliated Hospital, Jinan University, Guangzhou, 510630, Guangdong, China
| | - Jogendra Singh Pawar
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, 47906, IN, USA
| | - Huan-Tian Zhang
- Institute of Orthopedic Diseases and Department of Bone and Joint Surgery, the First Affiliated Hospital, Jinan University, Guangzhou, 510630, Guangdong, China.
| | - Zhen-Gang Zha
- Institute of Orthopedic Diseases and Department of Bone and Joint Surgery, the First Affiliated Hospital, Jinan University, Guangzhou, 510630, Guangdong, China.
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Fremuntova Z, Mosko T, Soukup J, Kucerova J, Kostelanska M, Hanusova ZB, Filipova M, Cervenakova L, Holada K. Changes in cellular prion protein expression, processing and localisation during differentiation of the neuronal cell line CAD 5. Biol Cell 2019; 112:1-21. [PMID: 31736091 DOI: 10.1111/boc.201900045] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 11/08/2019] [Accepted: 11/09/2019] [Indexed: 11/30/2022]
Abstract
BACKGROUND INFORMATION Cellular prion protein (PrPC ) is infamous for its role in prion diseases. The physiological function of PrPC remains enigmatic, but several studies point to its involvement in cell differentiation processes. To test this possibility, we monitored PrPC changes during the differentiation of prion-susceptible CAD 5 cells, and then we analysed the effect of PrPC ablation on the differentiation process. RESULTS Neuronal CAD 5 cells differentiate within 5 days of serum withdrawal, with the majority of the cells developing long neurites. This process is accompanied by an up to sixfold increase in PrPC expression and enhanced N-terminal β-cleavage of the protein, which suggests a role for the PrPC in the differentiation process. Moreover, the majority of PrPC in differentiated cells is inside the cell, and a large proportion of the protein does not associate with membrane lipid rafts. In contrast, PrPC in proliferating cells is found mostly on the cytoplasmic membrane and is predominantly associated with lipid rafts. To determine the importance of PrPC in cell differentiation, a CAD 5 PrP-/- cell line with ablated PrPC expression was created using the CRISPR/Cas9 system. We observed no considerable difference in morphology, proliferation rate or expression of molecular markers between CAD 5 and CAD 5 PrP-/- cells during the differentiation initiated by serum withdrawal. CONCLUSIONS PrPC characteristics, such as cell localisation, level of expression and posttranslational modifications, change during CAD 5 cell differentiation, but PrPC ablation does not change the course of the differentiation process. SIGNIFICANCE Ablation of PrPC expression does not affect CAD 5 cell differentiation, although we observed many intriguing changes in PrPC features during the process. Our study does not support the concept that PrPC is important for neuronal cell differentiation, at least in simple in vitro conditions.
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Affiliation(s)
- Zuzana Fremuntova
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Tibor Mosko
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Jakub Soukup
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic.,Department of Genetics and Microbiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Johanka Kucerova
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Marie Kostelanska
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Zdenka Backovska Hanusova
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Marcela Filipova
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | | | - Karel Holada
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
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Leyton L, Díaz J, Martínez S, Palacios E, Pérez LA, Pérez RD. Thy-1/CD90 a Bidirectional and Lateral Signaling Scaffold. Front Cell Dev Biol 2019; 7:132. [PMID: 31428610 PMCID: PMC6689999 DOI: 10.3389/fcell.2019.00132] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 07/04/2019] [Indexed: 01/18/2023] Open
Abstract
Thy-1/CD90 is a glycoprotein attached to the outer face of the plasma membrane with various functions, which depend on the context of specific physiological or pathological conditions. Many of these reported functions for Thy-1/CD90 arose from studies by our group, which identified the first ligand/receptor for Thy-1/CD90 as an integrin. This finding initiated studies directed toward unveiling the molecular mechanisms that operate downstream of Thy-1/CD90 activation, and its possible interaction with proteins in the membrane plane to regulate their function. The association of Thy-1/CD90 with a number of cell surface molecules allows the formation of extra/intracellular multiprotein complexes composed of various ligands and receptors, extracellular matrix proteins, intracellular signaling proteins, and the cytoskeleton. The complexes sense changes that occur inside and outside the cells, with Thy-1/CD90 at the core of this extracellular molecular platform. Molecular platforms are scaffold-containing microdomains where key proteins associate to prominently influence cellular processes and behavior. Each component, by itself, is less effective, but when together with various scaffold proteins to form a platform, the components become more specific and efficient to convey the messages. This review article discusses the experimental evidence that supports the role of Thy-1/CD90 as a membrane-associated platform (ThyMAP).
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Affiliation(s)
- Lisette Leyton
- Cellular Communication Laboratory, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Advanced Center for Chronic Diseases (ACCDiS), Center for Exercise, Metabolism and Cancer Studies (CEMC), Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Jorge Díaz
- Cellular Communication Laboratory, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Advanced Center for Chronic Diseases (ACCDiS), Center for Exercise, Metabolism and Cancer Studies (CEMC), Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Samuel Martínez
- Cellular Communication Laboratory, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Advanced Center for Chronic Diseases (ACCDiS), Center for Exercise, Metabolism and Cancer Studies (CEMC), Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Esteban Palacios
- Cellular Communication Laboratory, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Advanced Center for Chronic Diseases (ACCDiS), Center for Exercise, Metabolism and Cancer Studies (CEMC), Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Laboratorio de Microbiología Celular, Facultad de Ciencias de la Salud, Universidad Central de Chile, Santiago, Chile
| | - Leonardo A Pérez
- Cellular Communication Laboratory, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Advanced Center for Chronic Diseases (ACCDiS), Center for Exercise, Metabolism and Cancer Studies (CEMC), Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Ramón D Pérez
- Cellular Communication Laboratory, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Advanced Center for Chronic Diseases (ACCDiS), Center for Exercise, Metabolism and Cancer Studies (CEMC), Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
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7
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Lv Y, Zhou D, Hao XQ, Zhu MY, Zhang CD, Zhou DM, Wang JH, Liu RX, Wang YL, Gu WZ, Shen HQ, Chen X, Zhao ZY. A recombinant measles virus vaccine strain rMV-Hu191 has oncolytic effect against human gastric cancer by inducing apoptotic cell death requiring integrity of lipid raft microdomains. Cancer Lett 2019; 460:108-118. [PMID: 31226409 DOI: 10.1016/j.canlet.2019.06.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 06/05/2019] [Accepted: 06/13/2019] [Indexed: 12/16/2022]
Abstract
Live-attenuated strain of measles virus (MV) has oncolytic effect. In this study, the antitumor effect of rMV-Hu191, a recombinant Chinese Hu191 MV generated in our laboratory by efficient reverse genetics system, was evaluated in gastric cancer (GC). From our data, rMV-Hu191 induced cytopathic effects and inhibited tumor proliferation both in vitro and in vivo by inducing caspase-dependent apoptosis. In mice bearing GC xenografts, tumor size was reduced and survival was prolonged significantly after intratumoral injections of rMV-Hu191. Furthermore, lipid rafts, a type of membrane microdomain with specific lipid compositions, played an important role in facilitating entry of rMV-Hu191. Integrity of lipid rafts was required for successful viral infection as well as subsequent cell apoptosis, but was not required for viral binding and replication. CD46, a MV membrane receptor, was found to be partially localized in lipid rafts microdomains. This is the first study to demonstrate that Chinese Hu191 MV vaccine strain could be used as a potentially effective therapeutic agent in GC treatment. As part of the underlying cellular mechanism, the integrity of lipid rafts is required for viral entry and to exercise the oncolytic effect.
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Affiliation(s)
- Yao Lv
- Zhejiang University School of Medicine, Hangzhou, 310000, Zhejiang, China.
| | - Duo Zhou
- Zhejiang University School of Medicine, Hangzhou, 310000, Zhejiang, China.
| | - Xiao-Qiang Hao
- Zhejiang University School of Medicine, Hangzhou, 310000, Zhejiang, China.
| | - Meng-Ying Zhu
- Zhejiang University School of Medicine, Hangzhou, 310000, Zhejiang, China.
| | - Chu-di Zhang
- Zhejiang University School of Medicine, Hangzhou, 310000, Zhejiang, China.
| | - Dong-Ming Zhou
- Children's Hospital, Zhejiang University School of Medicine, Hangzhou, 310052, Zhejiang, China.
| | - Jin-Hu Wang
- Children's Hospital, Zhejiang University School of Medicine, Hangzhou, 310052, Zhejiang, China.
| | - Rong-Xian Liu
- Zhejiang University School of Medicine, Hangzhou, 310000, Zhejiang, China.
| | - Yi-Long Wang
- Children's Hospital, Zhejiang University School of Medicine, Hangzhou, 310052, Zhejiang, China.
| | - Wei-Zhong Gu
- Children's Hospital, Zhejiang University School of Medicine, Hangzhou, 310052, Zhejiang, China; Key Laboratory of Diagnosis and Treatment of Neonatal Diseases of Zhejiang Province, Hangzhou, 310052, Zhejiang, China.
| | - Hong-Qiang Shen
- Children's Hospital, Zhejiang University School of Medicine, Hangzhou, 310052, Zhejiang, China; Key Laboratory of Diagnosis and Treatment of Neonatal Diseases of Zhejiang Province, Hangzhou, 310052, Zhejiang, China.
| | - Xi Chen
- Zhejiang University School of Medicine, Hangzhou, 310000, Zhejiang, China; Children's Hospital, Zhejiang University School of Medicine, Hangzhou, 310052, Zhejiang, China; Key Laboratory of Diagnosis and Treatment of Neonatal Diseases of Zhejiang Province, Hangzhou, 310052, Zhejiang, China.
| | - Zheng-Yan Zhao
- Zhejiang University School of Medicine, Hangzhou, 310000, Zhejiang, China; Children's Hospital, Zhejiang University School of Medicine, Hangzhou, 310052, Zhejiang, China; Key Laboratory of Diagnosis and Treatment of Neonatal Diseases of Zhejiang Province, Hangzhou, 310052, Zhejiang, China.
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8
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Ilic K, Auer B, Mlinac-Jerkovic K, Herrera-Molina R. Neuronal Signaling by Thy-1 in Nanodomains With Specific Ganglioside Composition: Shall We Open the Door to a New Complexity? Front Cell Dev Biol 2019; 7:27. [PMID: 30899760 PMCID: PMC6416198 DOI: 10.3389/fcell.2019.00027] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 02/15/2019] [Indexed: 01/06/2023] Open
Abstract
Thy-1 is a small membrane glycoprotein and member of the immunoglobulin superfamily of cell adhesion molecules. It is abundantly expressed in many cell types including neurons and is anchored to the outer membrane leaflet via a glycosyl phosphatidylinositol tail. Thy-1 displays a number of interesting properties such as fast lateral diffusion, which allows it to get in and out of membrane nanodomains with different lipid composition. Thy-1 displays a broad expression in different cell types and plays confirmed roles in cell development, adhesion and differentiation. Here, we explored the functions of Thy-1 in neuronal signaling, initiated by extracellular binding of αVβ3 integrin, may strongly dependent on the lipid content of the cell membrane. Also, we assort literature suggesting the association of Thy-1 with specific components of lipid rafts such as sialic acid containing glycosphingolipids, called gangliosides. Furthermore, we argue that Thy-1 positioning in nanodomains may be influenced by gangliosides. We propose that the traditional conception of Thy-1 localization in rafts should be reconsidered and evaluated in detail based on the potential diversity of neuronal nanodomains.
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Affiliation(s)
- Katarina Ilic
- Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Benedikt Auer
- Laboratory of Neuronal and Synaptic Signals, Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Kristina Mlinac-Jerkovic
- Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Rodrigo Herrera-Molina
- Laboratory of Neuronal and Synaptic Signals, Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany.,Centro Integrativo de Biología y Química Aplicada, Universidad Bernardo O'Higgins, Santiago, Chile
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9
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GPI-anchor signal sequence influences PrPC sorting, shedding and signalling, and impacts on different pathomechanistic aspects of prion disease in mice. PLoS Pathog 2019; 15:e1007520. [PMID: 30608982 PMCID: PMC6334958 DOI: 10.1371/journal.ppat.1007520] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 01/16/2019] [Accepted: 12/11/2018] [Indexed: 12/31/2022] Open
Abstract
The cellular prion protein (PrPC) is a cell surface glycoprotein attached to the membrane by a glycosylphosphatidylinositol (GPI)-anchor and plays a critical role in transmissible, neurodegenerative and fatal prion diseases. Alterations in membrane attachment influence PrPC-associated signaling, and the development of prion disease, yet our knowledge of the role of the GPI-anchor in localization, processing, and function of PrPCin vivo is limited We exchanged the PrPC GPI-anchor signal sequence of for that of Thy-1 (PrPCGPIThy-1) in cells and mice. We show that this modifies the GPI-anchor composition, which then lacks sialic acid, and that PrPCGPIThy-1 is preferentially localized in axons and is less prone to proteolytic shedding when compared to PrPC. Interestingly, after prion infection, mice expressing PrPCGPIThy-1 show a significant delay to terminal disease, a decrease of microglia/astrocyte activation, and altered MAPK signaling when compared to wild-type mice. Our results are the first to demonstrate in vivo, that the GPI-anchor signal sequence plays a fundamental role in the GPI-anchor composition, dictating the subcellular localization of a given protein and, in the case of PrPC, influencing the development of prion disease. The prion protein (PrPC) is a glycoprotein attached to the neuronal surface via a GPI-anchor. When misfolded to PrPSc, it leads to fatal neurodegenerative diseases which propagates from host to host. PrPSc is the principal component of the infectious agent of prion diseases, the “prion”. Misfolding occurs at the plasma membrane, and when PrPC lacks the GPI-anchor, neuropathology and incubation time of prion disease are strongly modified. Moreover, the composition of the PrPC GPI-anchor impacts on the conversion process. To study the role of the GPI-anchor in the pathophysiology of prion diseases in vivo, we have generated transgenic mice where the PrPC GPI-signal sequence (GPI-SS) is replaced for the one of Thy-1, a neuronal protein with a distinct GPI-anchor and membrane localization. We found that the resulting protein, PrPCGPIThy-1, shows a different GPI-anchor composition, increased axonal localization, and reduced enzymatic shedding. After prion infection, disease progression is significantly delayed, and the neuropathology and cellular signaling are changed. The present work demonstrates that the GPI-SS per se determines the GPI-anchor composition and localization of a given protein and it stresses the importance of PrPC membrane anchorage in prion disease.
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10
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Morris RJ. Thy-1, a Pathfinder Protein for the Post-genomic Era. Front Cell Dev Biol 2018; 6:173. [PMID: 30619853 PMCID: PMC6305390 DOI: 10.3389/fcell.2018.00173] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 12/06/2018] [Indexed: 12/21/2022] Open
Abstract
Thy-1 is possibly the smallest of cell surface proteins – 110 amino acids folded into an Immunoglobulin variable domain, tethered to the outer leaflet of the cell surface membrane via just the two saturated fatty acids of its glycosylphosphatidylinositol (GPI) anchor. Yet Thy-1 is emerging as a key regulator of differentiation in cells of endodermal, mesodermal, and ectodermal origin, acting as both a ligand (for certain integrins and other receptors), and as a receptor, able to modulate signaling and hence differentiation in the Thy-1-expressing cell. This is an extraordinary diversity of molecular pathways to be controlled by a molecule that does not even cross the cell membrane. Here I review aspects of the cell biology of Thy-1, and studies of its role as deduced from gene knock-out studies, that suggest how this protein can participate in so many different signaling-related functions. While mechanisms differ in molecular detail, it appears overall that Thy-1 dampens down signaling to control function.
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Affiliation(s)
- Roger J Morris
- Department of Chemistry, King's College London, London, United Kingdom
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11
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Bieberich E. Sphingolipids and lipid rafts: Novel concepts and methods of analysis. Chem Phys Lipids 2018; 216:114-131. [PMID: 30194926 PMCID: PMC6196108 DOI: 10.1016/j.chemphyslip.2018.08.003] [Citation(s) in RCA: 133] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/20/2018] [Accepted: 08/25/2018] [Indexed: 12/12/2022]
Abstract
About twenty years ago, the functional lipid raft model of the plasma membrane was published. It took into account decades of research showing that cellular membranes are not just homogenous mixtures of lipids and proteins. Lateral anisotropy leads to assembly of membrane domains with specific lipid and protein composition regulating vesicular traffic, cell polarity, and cell signaling pathways in a plethora of biological processes. However, what appeared to be a clearly defined entity of clustered raft lipids and proteins became increasingly fluid over the years, and many of the fundamental questions about biogenesis and structure of lipid rafts remained unanswered. Experimental obstacles in visualizing lipids and their interactions hampered progress in understanding just how big rafts are, where and when they are formed, and with which proteins raft lipids interact. In recent years, we have begun to answer some of these questions and sphingolipids may take center stage in re-defining the meaning and functional significance of lipid rafts. In addition to the archetypical cholesterol-sphingomyelin raft with liquid ordered (Lo) phase and the liquid-disordered (Ld) non-raft regions of cellular membranes, a third type of microdomains termed ceramide-rich platforms (CRPs) with gel-like structure has been identified. CRPs are "ceramide rafts" that may offer some fresh view on the membrane mesostructure and answer several critical questions for our understanding of lipid rafts.
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Affiliation(s)
- Erhard Bieberich
- Department of Physiology at the University of Kentucky, Lexington, KY, United States.
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Skotland T, Sandvig K, Llorente A. Lipids in exosomes: Current knowledge and the way forward. Prog Lipid Res 2017; 66:30-41. [PMID: 28342835 DOI: 10.1016/j.plipres.2017.03.001] [Citation(s) in RCA: 654] [Impact Index Per Article: 93.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 03/14/2017] [Accepted: 03/21/2017] [Indexed: 12/29/2022]
Abstract
Lipids are essential components of exosomal membranes, and it is well-known that specific lipids are enriched in exosomes compared to their parent cells. In this review we discuss current knowledge about the lipid composition of exosomes. We compare published data for different lipid classes in exosomes, and what is known about their lipid species, i.e. lipid molecules with different fatty acyl groups. Moreover, we elaborate on the hypothesis about hand-shaking between the very-long-chain sphingolipids in the outer leaflet and PS 18:0/18:1 in the inner leaflet, and we propose this to be an important mechanism in membrane biology, not only for exosomes. The similarity between the lipid composition of exosomes, HIV particles, and detergent resistant membranes, used as lipid rafts models, is also discussed. Furthermore, we summarize knowledge about the role of specific lipids and lipid metabolizing enzymes on the formation and release of exosomes. Finally, the use of exosomal lipids as biomarkers and how the lipid composition of exosomes may be of importance for researchers aiming to use exosomes as drug delivery vehicles is discussed. In conclusion, we have summarized what is presently known about lipids in exosomes and identified issues that should be taken into consideration in future studies.
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Affiliation(s)
- Tore Skotland
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital-The Norwegian Radium Hospital, 0379 Oslo, Norway; Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0379 Oslo, Norway.
| | - Kirsten Sandvig
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital-The Norwegian Radium Hospital, 0379 Oslo, Norway; Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0379 Oslo, Norway; Department of Molecular Biosciences, University of Oslo, 0316 Oslo, Norway
| | - Alicia Llorente
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital-The Norwegian Radium Hospital, 0379 Oslo, Norway; Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0379 Oslo, Norway
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Ballek O, Valečka J, Dobešová M, Broučková A, Manning J, Řehulka P, Stulík J, Filipp D. TCR Triggering Induces the Formation of Lck-RACK1-Actinin-1 Multiprotein Network Affecting Lck Redistribution. Front Immunol 2016; 7:449. [PMID: 27833610 PMCID: PMC5081367 DOI: 10.3389/fimmu.2016.00449] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 10/10/2016] [Indexed: 02/02/2023] Open
Abstract
The initiation of T-cell signaling is critically dependent on the function of the member of Src family tyrosine kinases, Lck. Upon T-cell antigen receptor (TCR) triggering, Lck kinase activity induces the nucleation of signal-transducing hubs that regulate the formation of complex signaling network and cytoskeletal rearrangement. In addition, the delivery of Lck function requires rapid and targeted membrane redistribution, but the mechanism underpinning this process is largely unknown. To gain insight into this process, we considered previously described proteins that could assist in this process via their capacity to interact with kinases and regulate their intracellular translocations. An adaptor protein, receptor for activated C kinase 1 (RACK1), was chosen as a viable option, and its capacity to bind Lck and aid the process of activation-induced redistribution of Lck was assessed. Our microscopic observation showed that T-cell activation induces a rapid, concomitant, and transient co-redistribution of Lck and RACK1 into the forming immunological synapse. Consistent with this observation, the formation of transient RACK1-Lck complexes were detectable in primary CD4+ T-cells with their maximum levels peaking 10 s after TCR-CD4 co-aggregation. Moreover, RACK1 preferentially binds to a pool of kinase active pY394Lck, which co-purifies with high molecular weight cellular fractions. The formation of RACK1-Lck complexes depends on functional SH2 and SH3 domains of Lck and includes several other signaling and cytoskeletal elements that transiently bind the complex. Notably, the F-actin-crosslinking protein, α-actinin-1, binds to RACK1 only in the presence of kinase active Lck suggesting that the formation of RACK1-pY394Lck-α-actinin-1 complex serves as a signal module coupling actin cytoskeleton bundling with productive TCR/CD4 triggering. In addition, the treatment of CD4+ T-cells with nocodazole, which disrupts the microtubular network, also blocked the formation of RACK1-Lck complexes. Importantly, activation-induced Lck redistribution was diminished in primary CD4+ T-cells by an adenoviral-mediated knockdown of RACK1. These results demonstrate that in T cells, RACK1, as an essential component of the multiprotein complex which upon TCR engagement, links the binding of kinase active Lck to elements of the cytoskeletal network and affects the subcellular redistribution of Lck.
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Affiliation(s)
- Ondřej Ballek
- Laboratory of Immunobiology, Institute of Molecular Genetics AS CR , Prague , Czech Republic
| | - Jan Valečka
- Laboratory of Immunobiology, Institute of Molecular Genetics AS CR , Prague , Czech Republic
| | - Martina Dobešová
- Laboratory of Immunobiology, Institute of Molecular Genetics AS CR , Prague , Czech Republic
| | - Adéla Broučková
- Laboratory of Immunobiology, Institute of Molecular Genetics AS CR , Prague , Czech Republic
| | - Jasper Manning
- Laboratory of Immunobiology, Institute of Molecular Genetics AS CR , Prague , Czech Republic
| | - Pavel Řehulka
- Faculty of Military Health Sciences, Institute of Molecular Pathology , Hradec Králové , Czech Republic
| | - Jiří Stulík
- Faculty of Military Health Sciences, Institute of Molecular Pathology , Hradec Králové , Czech Republic
| | - Dominik Filipp
- Laboratory of Immunobiology, Institute of Molecular Genetics AS CR , Prague , Czech Republic
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Wang Z, Schey KL. Proteomic Analysis of Lipid Raft-Like Detergent-Resistant Membranes of Lens Fiber Cells. Invest Ophthalmol Vis Sci 2016; 56:8349-60. [PMID: 26747763 DOI: 10.1167/iovs.15-18273] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Plasma membranes of lens fiber cells have high levels of long-chain saturated fatty acids, cholesterol, and sphingolipids-key components of lipid rafts. Thus, lipid rafts are expected to constitute a significant portion of fiber cell membranes and play important roles in lens biology. The purpose of this study was to characterize the lens lipid raft proteome. METHODS Quantitative proteomics, both label-free and iTRAQ methods, were used to characterize lens fiber cell lipid raft proteins. Detergent-resistant, lipid raft membrane (DRM) fractions were isolated by sucrose gradient centrifugation. To confirm protein localization to lipid rafts, protein sensitivity to cholesterol removal by methyl-β-cyclodextrin was quantified by iTRAQ analysis. RESULTS A total of 506 proteins were identified in raft-like detergent-resistant membranes. Proteins identified support important functions of raft domains in fiber cells, including trafficking, signal transduction, and cytoskeletal organization. In cholesterol-sensitivity studies, 200 proteins were quantified and 71 proteins were strongly affected by cholesterol removal. Lipid raft markers flotillin-1 and flotillin-2 and a significant fraction of AQP0, MP20, and AQP5 were found in the DRM fraction and were highly sensitive to cholesterol removal. Connexins 46 and 50 were more abundant in nonraft fractions, but a small fraction of each was found in the DRM fraction and was strongly affected by cholesterol removal. Quantification of modified AQP0 confirmed that fatty acylation targeted this protein to membrane raft domains. CONCLUSIONS These data represent the first comprehensive profile of the lipid raft proteome of lens fiber cells and provide information on membrane protein organization in these cells.
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Abstract
The hypothesis that the Golgi apparatus is capable of sorting proteins and sending them to the plasma membrane through "lipid rafts," membrane lipid domains highly enriched in glycosphingolipids, sphingomyelin, ceramide, and cholesterol, was formulated by van Meer and Simons in 1988 and came to a turning point when it was suggested that lipid rafts could be isolated thanks to their resistance to solubilization by some detergents, namely Triton X-100. An incredible number of papers have described the composition and properties of detergent-resistant membrane fractions. However, the use of this method has also raised the fiercest criticisms. In this chapter, we would like to discuss the most relevant methodological aspects related to the preparation of detergent-resistant membrane fractions, and to discuss the importance of discriminating between what is present on a cell membrane and what we can prepare from cell membranes in a laboratory tube.
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Leyton L, Hagood JS. Thy-1 Modulates Neurological Cell–Cell and Cell–Matrix Interactions Through Multiple Molecular Interactions. ADVANCES IN NEUROBIOLOGY 2014; 8:3-20. [DOI: 10.1007/978-1-4614-8090-7_1] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Cubí R, Matas LA, Pou M, Aguilera J, Gil C. Differential sensitivity to detergents of actin cytoskeleton from nerve endings. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2385-93. [PMID: 23817010 DOI: 10.1016/j.bbamem.2013.06.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 06/13/2013] [Accepted: 06/17/2013] [Indexed: 01/13/2023]
Abstract
Detergent-resistant membranes (DRM), an experimental model used to study lipid rafts, are typically extracted from cells by means of detergent treatment and subsequent ultracentrifugation in density gradients, Triton X-100 being the detergent of choice in most of the works. Since lipid rafts are membrane microdomains rich in cholesterol, depletion of this component causes solubilization of DRM with detergent. In previous works from our group, the lack of effect of cholesterol depletion on DRM solubilization with Triton X-100 was detected in isolated rat brain synaptosomes. In consequence, the aim of the present work is to explore reasons for this observation, analyzing the possible role of the actin cytoskeleton, as well as the use of an alternative detergent, Brij 98, to overcome the insensitivity to Triton X-100 of cholesterol-depleted DRM. Brij 98 yields Brij-DRM that are highly dependent on cholesterol, since marker proteins (Flotillin-1 and Thy-1), as well as actin, appear solubilized after MCD treatment. Pretreatment with Latrunculin A results in a significant increase in Flotillin-1, Thy-1 and actin solubilization by Triton X-100 after cholesterol depletion. Studies with transmission electron microscopy show that combined treatment with MCD and Latrunculin A leads to a significant increase in solubilization of DRM with Triton X-100. Thus, Triton-DRM resistance to cholesterol depletion can be explained, at least partially, thanks to the scaffolding action of the actin cytoskeleton, without discarding differential effects of Brij 98 and Triton X-100 on specific membrane components. In conclusion, the detergent of choice is important when events that depend on the actin cytoskeleton are going to be studied.
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Affiliation(s)
- Roger Cubí
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra 08193, Catalunya, Spain; Institut de Neurociències, Universitat Autònoma de Barcelona, Spain
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Abstract
Mutations within the central region of prion protein (PrP) have been shown to be associated with severe neurotoxic activity similar to that observed with Dpl, a PrP-like protein. To further investigate this neurotoxic effect, we generated lines of transgenic (Tg) mice expressing three different chimeric PrP-Dpl proteins. Chi1 (amino acids 1-57 of Dpl replaced by amino acids 1-125 of PrP) and Chi2 (amino acids 1-66 of Dpl replaced by amino acids 1-134 of PrP) abrogated the pathogenicity of Dpl indicating that the presence of a N-terminal domain of PrP (23-134) reduced the toxicity of Dpl, as reported. However, when the amino acids 1-24 of Dpl were replaced by amino acids 1-124 of PrP, Chi3 Tg mice, which express the chimeric protein at a very low level, start developing ataxia at the age of 5-7 weeks. This phenotype was not counteracted by a single copy of full-length-PrP(c) but rather by its overexpression, indicating the strong toxicity of the chimeric protein Chi3. Chi3 Tg mice exhibit severe cerebellar atrophy with a significant loss of granule cells. We concluded that aa25 to aa57 of Dpl, which are not present in Chi1 and Chi2 constructs, confer toxicity to the protein. We tested this possibility by using the 25-57 Dpl peptide in primary culture of mouse embryo cortical neurons and found a significant neurotoxic effect. This finding identifies a protein domain that plays a role in mediating Dpl-related toxicity.
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Abstract
There is growing evidence that cell membranes can contain domains with different lipid and protein compositions and with different physical properties. Furthermore, it is increasingly appreciated that sphingolipids play a crucial role in the formation and properties of ordered lipid domains (rafts) in cell membranes. This review describes recent advances in our understanding of ordered membrane domains in both cells and model membranes. In addition, how the structure of sphingolipids influences their ability to participate in the formation of ordered domains, as well as how sphingolipid structure alters ordered domain properties, is described. The diversity of sphingolipid structure is likely to play an important role in modulating the biologically relevant properties of "rafts" in cell membranes.
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Thy-1-Interacting Molecules and Cellular Signaling in Cis and Trans. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 305:163-216. [DOI: 10.1016/b978-0-12-407695-2.00004-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Hicks DA, Nalivaeva NN, Turner AJ. Lipid rafts and Alzheimer's disease: protein-lipid interactions and perturbation of signaling. Front Physiol 2012; 3:189. [PMID: 22737128 PMCID: PMC3381238 DOI: 10.3389/fphys.2012.00189] [Citation(s) in RCA: 142] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 05/21/2012] [Indexed: 12/16/2022] Open
Abstract
Lipid rafts are membrane domains, more ordered than the bulk membrane and enriched in cholesterol and sphingolipids. They represent a platform for protein-lipid and protein–protein interactions and for cellular signaling events. In addition to their normal functions, including membrane trafficking, ligand binding (including viruses), axonal development and maintenance of synaptic integrity, rafts have also been implicated in the pathogenesis of several neurodegenerative diseases including Alzheimer’s disease (AD). Lipid rafts promote interaction of the amyloid precursor protein (APP) with the secretase (BACE-1) responsible for generation of the amyloid β peptide, Aβ. Rafts also regulate cholinergic signaling as well as acetylcholinesterase and Aβ interaction. In addition, such major lipid raft components as cholesterol and GM1 ganglioside have been directly implicated in pathogenesis of the disease. Perturbation of lipid raft integrity can also affect various signaling pathways leading to cellular death and AD. In this review, we discuss modulation of APP cleavage by lipid rafts and their components, while also looking at more recent findings on the role of lipid rafts in signaling events.
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Affiliation(s)
- David A Hicks
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds Leeds, UK
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Filipp D, Ballek O, Manning J. Lck, Membrane Microdomains, and TCR Triggering Machinery: Defining the New Rules of Engagement. Front Immunol 2012; 3:155. [PMID: 22701458 PMCID: PMC3372939 DOI: 10.3389/fimmu.2012.00155] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 05/25/2012] [Indexed: 11/21/2022] Open
Abstract
In spite of a comprehensive understanding of the schematics of T cell receptor (TCR) signaling, the mechanisms regulating compartmentalization of signaling molecules, their transient interactions, and rearrangement of membrane structures initiated upon TCR engagement remain an outstanding problem. These gaps in our knowledge are exemplified by recent data demonstrating that TCR triggering is largely dependent on a preactivated pool of Lck concentrated in T cells in a specific type of membrane microdomains. Our current model posits that in resting T cells all critical components of TCR triggering machinery including TCR/CD3, Lck, Fyn, CD45, PAG, and LAT are associated with distinct types of lipid-based microdomains which represent the smallest structural and functional units of membrane confinement able to negatively control enzymatic activities and substrate availability that is required for the initiation of TCR signaling. In addition, the microdomains based segregation spatially limits the interaction of components of TCR triggering machinery prior to the onset of TCR signaling and allows their rapid communication and signal amplification after TCR engagement, via the process of their coalescence. Microdomains mediated compartmentalization thus represents an essential membrane organizing principle in resting T cells. The integration of these structural and functional aspects of signaling into a unified model of TCR triggering will require a deeper understanding of membrane biology, novel interdisciplinary approaches and the generation of specific reagents. We believe that the fully integrated model of TCR signaling must be based on membrane structural network which provides a proper environment for regulatory processes controlling TCR triggering.
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Affiliation(s)
- Dominik Filipp
- Laboratory of Immunobiology, Institute of Molecular Genetics AS CR Prague, Czech Republic
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Curvature factor and membrane solubilization, with particular reference to membrane rafts. Cell Biol Int 2012; 35:991-5. [PMID: 21438858 DOI: 10.1042/cbi20100786] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The composition of membrane rafts (cholesterol/sphingolipid-rich domains) cannot be fully deduced from the analysis of a detergent-resistant membrane fraction after solubilization in Triton X-100 at 4°C. It is hypothesized that the membrane curvature-dependent lateral distribution of membrane components affects their solubilization. The stomatocytogenic, Triton X-100, cannot effectively solubilize membrane components, especially with regard to the outward membrane curvature.
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Baron GS, Hughson AG, Raymond GJ, Offerdahl DK, Barton KA, Raymond LD, Dorward DW, Caughey B. Effect of glycans and the glycophosphatidylinositol anchor on strain dependent conformations of scrapie prion protein: improved purifications and infrared spectra. Biochemistry 2011; 50:4479-90. [PMID: 21539311 PMCID: PMC3101284 DOI: 10.1021/bi2003907] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mammalian prion diseases involve conversion of normal prion protein, PrP(C), to a pathological aggregated state (PrP(res)). The three-dimensional structure of PrP(res) is not known, but infrared (IR) spectroscopy has indicated high, strain-dependent β-sheet content. PrP(res) molecules usually contain a glycophosphatidylinositol (GPI) anchor and large Asn-linked glycans, which can also vary with strain. Using IR spectroscopy, we tested the conformational effects of these post-translational modifications by comparing wild-type PrP(res) with GPI- and glycan-deficient PrP(res) produced in GPI-anchorless PrP transgenic mice. These analyses required the development of substantially improved purification protocols. Spectra of both types of PrP(res) revealed conformational differences between the 22L, ME7, and Chandler (RML) murine scrapie strains, most notably in bands attributed to β-sheets. These PrP(res) spectra were also distinct from those of the hamster 263K scrapie strain. Spectra of wild-type and anchorless 22L PrP(res) were nearly indistinguishable. With ME7 PrP(res), modest differences between the wild-type and anchorless spectra were detected, notably an ∼2 cm(-1) shift in an apparent β-sheet band. Collectively, the data provide evidence that the glycans and anchor do not grossly affect the strain-specific secondary structures of PrP(res), at least relative to the differences observed between strains, but can subtly affect turns and certain β-sheet components. Recently reported H-D exchange analyses of anchorless PrP(res) preparations strongly suggested the presence of strain-dependent, solvent-inaccessible β-core structures throughout most of the C-terminal half of PrP(res) molecules, with no remaining α-helix. Our IR data provide evidence that similar core structures also comprise wild-type PrP(res).
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Affiliation(s)
- Gerald S. Baron
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840
| | - Andrew G. Hughson
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840
| | - Gregory J. Raymond
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840
| | - Danielle K. Offerdahl
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840
| | - Kelly A. Barton
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840
| | - Lynne D. Raymond
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840
| | - David W. Dorward
- Microscopy Unit, Research Technology Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840
| | - Byron Caughey
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840
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Morris RJ, Jen A, Warley A. Isolation of nano-meso scale detergent resistant membrane that has properties expected of lipid ‘rafts’. J Neurochem 2011; 116:671-7. [DOI: 10.1111/j.1471-4159.2010.07076.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Huang H, Feng X, Zhuang J, Fröhlich O, Klein JD, Cai H, Sands JM, Chen G. Internalization of UT-A1 urea transporter is dynamin dependent and mediated by both caveolae- and clathrin-coated pit pathways. Am J Physiol Renal Physiol 2010; 299:F1389-95. [PMID: 20861071 PMCID: PMC3006306 DOI: 10.1152/ajprenal.00718.2009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Accepted: 09/20/2010] [Indexed: 11/22/2022] Open
Abstract
Dynamin is a large GTPase involved in several distinct modes of cell endocytosis. In this study, we examined the possible role of dynamin in UT-A1 internalization. The direct relationship of UT-A1 and dynamin was identified by coimmunoprecipitation. UT-A1 has cytosolic NH(2) and COOH termini and a large intracellular loop. Dynamin specifically binds to the intracellular loop of UT-A1, but not the NH(2) and COOH termini. In cell surface biotinylation experiments, coexpression of dynamin and UT-A1 in HEK293 cells resulted in a decrease of UT-A1 cell surface expression. Conversely, cells expressing dynamin mutant K44A, which is deficient in GTP binding, showed an increased accumulation of UT-A1 protein on the cell surface. Cell plasma membrane lipid raft fractionation experiments revealed that blocking endocytosis with dynamin K44A causes UT-A1 protein accumulation in both the lipid raft and nonlipid raft pools, suggesting that both caveolae- and clathrin-mediated mechanisms may be involved in the internalization of UT-A1. This was further supported by 1) small interfering RNA to knock down either caveolin-1 or μ2 reduced UT-A1 internalization in HEK293 cells and 2) inhibition of either the caveolae pathway by methyl-β-cyclodextrin or the clathrin pathway by concanavalin A caused UT-A1 cell membrane accumulation. Functionally, overexpression of dynamin, caveolin, or μ2 decreased UT-A1 urea transport activity and decreased UT-A1 cell surface expression. We conclude that UT-A1 endocytosis is dynamin-dependent and mediated by both caveolae- and clathrin-coated pit pathways.
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Affiliation(s)
- Haidong Huang
- Department of Medicine, Renal Division, School of Medicine, Emory University, Atlanta, Georgia, USA
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Mahfoud R, Manis A, Binnington B, Ackerley C, Lingwood CA. A major fraction of glycosphingolipids in model and cellular cholesterol-containing membranes is undetectable by their binding proteins. J Biol Chem 2010; 285:36049-59. [PMID: 20716521 PMCID: PMC2975227 DOI: 10.1074/jbc.m110.110189] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Revised: 07/23/2010] [Indexed: 11/06/2022] Open
Abstract
Glycosphingolipids (GSLs) accumulate in cholesterol-enriched cell membrane domains and provide receptors for protein ligands. Lipid-based "aglycone" interactions can influence GSL carbohydrate epitope presentation. To evaluate this relationship, Verotoxin binding its receptor GSL, globotriaosyl ceramide (Gb(3)), was analyzed in simple GSL/cholesterol, detergent-resistant membrane vesicles by equilibrium density gradient centrifugation. Vesicles separated into two Gb(3/)cholesterol-containing populations. The lighter, minor fraction (<5% total GSL), bound VT1, VT2, IgG/IgM mAb anti-Gb(3), HIVgp120 or Bandeiraea simplicifolia lectin. Only IgM anti-Gb(3), more tolerant of carbohydrate modification, bound both vesicle fractions. Post-embedding cryo-immuno-EM confirmed these results. This appears to be a general GSL-cholesterol property, because similar receptor-inactive vesicles were separated for other GSL-protein ligand systems; cholera toxin (CTx)-GM1, HIVgp120-galactosyl ceramide/sulfatide. Inclusion of galactosyl or glucosyl ceramide (GalCer and GlcCer) rendered VT1-unreactive Gb(3)/cholesterol vesicles, VT1-reactive. We found GalCer and GlcCer bind Gb(3), suggesting GSL-GSL interaction can counter cholesterol masking of Gb(3). The similar separation of Vero cell membrane-derived vesicles into minor "binding," and major "non-binding" fractions when probed with VT1, CTx, or anti-SSEA4 (a human GSL stem cell marker), demonstrates potential physiological relevance. Cell membrane GSL masking was cholesterol- and actin-dependent. Cholesterol depletion of Vero and HeLa cells enabled differential VT1B subunit labeling of "available" and "cholesterol-masked" plasma membrane Gb(3) pools by fluorescence microscopy. Thus, the model GSL/cholesterol vesicle studies predicted two distinct membrane GSL formats, which were demonstrated within the plasma membrane of cultured cells. Cholesterol masking of most cell membrane GSLs may impinge many GSL receptor functions.
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Affiliation(s)
- Radhia Mahfoud
- From the Division of Molecular Structure and Function, Research Institute, and
| | - Adam Manis
- From the Division of Molecular Structure and Function, Research Institute, and
- the Departments of Laboratory Medicine & Pathology and
| | - Beth Binnington
- From the Division of Molecular Structure and Function, Research Institute, and
| | - Cameron Ackerley
- the Department of Pediatric Laboratory Medicine, The Hospital for Sick Children, Ontario M5G 1X8 and
| | - Clifford A. Lingwood
- From the Division of Molecular Structure and Function, Research Institute, and
- the Department of Pediatric Laboratory Medicine, The Hospital for Sick Children, Ontario M5G 1X8 and
- the Departments of Laboratory Medicine & Pathology and
- Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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Ruiz A, Hill MS, Schmitt K, Stephens EB. Membrane raft association of the Vpu protein of human immunodeficiency virus type 1 correlates with enhanced virus release. Virology 2010; 408:89-102. [PMID: 20880565 DOI: 10.1016/j.virol.2010.08.031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 08/05/2010] [Accepted: 08/26/2010] [Indexed: 11/26/2022]
Abstract
The Vpu protein of human immunodeficiency virus type 1 (HIV-1) is known to enhance virion release from certain cell types. To accomplish this function, Vpu interacts with the restriction factor known as bone marrow stromal cell antigen 2 (BST-2)/tetherin. In this study, we analyzed whether the Vpu protein is associated with microdomains known as lipid or membrane rafts. Our results indicate that Vpu partially partitions into detergent-resistant membrane (DRM) fractions when expressed alone or in the context of simian-human immunodeficiency virus (SHIV) infection. The ability to be partitioned into rafts was observed with both subtype B and C Vpu proteins. The use of cholesterol lowering lovastatin/M-β-cyclodextrin and co-patching experiments confirmed that Vpu can be detected in cholesterol rich regions of membranes. Finally, we present data showing that raft association-defective transmembrane mutants of Vpu have impaired enhanced virus release function, but still maintain the ability to down-regulate CD4.
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Affiliation(s)
- Autumn Ruiz
- Department of Anatomy and Cell Biology, University of Kansas Medical Center 3901 Rainbow Blvd. Kansas City, Kansas 66160
| | - M Sarah Hill
- Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center 3901 Rainbow Blvd. Kansas City, Kansas 66160
| | - Kimberly Schmitt
- Department of Anatomy and Cell Biology, University of Kansas Medical Center 3901 Rainbow Blvd. Kansas City, Kansas 66160
| | - Edward B Stephens
- Department of Anatomy and Cell Biology, University of Kansas Medical Center 3901 Rainbow Blvd. Kansas City, Kansas 66160.,Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center 3901 Rainbow Blvd. Kansas City, Kansas 66160
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31
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Quinn PJ. A lipid matrix model of membrane raft structure. Prog Lipid Res 2010; 49:390-406. [PMID: 20478335 DOI: 10.1016/j.plipres.2010.05.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 05/06/2010] [Indexed: 12/12/2022]
Abstract
Domains in cell membranes are created by lipid-lipid interactions and are referred to as membrane rafts. Reliable isolation methods have been developed which have shown that rafts from the same membranes have different proteins and can be sub-fractionated by immunoaffinity methods. Analysis of these raft subfractions shows that they are also comprised of different molecular species of lipids. The major lipid classes present are phospholipids, glycosphingolipids and cholesterol. Model studies show that mixtures of phospholipids, particularly sphingomyelin, and cholesterol form liquid-ordered phase with properties intermediate between a gel and fluid phase. This type of liquid-ordered phase dominates theories of domain formation and raft structure in biological membranes. Recently it has been shown that sphingolipids with long (22-26C) N-acyl fatty acids form quasi-crystalline bilayer structures with diacylphospholipids that have well-defined stoichiometries. A two tier heuristic model of membrane raft structure is proposed in which liquid-ordered phase created by a molecular complex between sphingolipids with hydrocarbon chains of approximately equal length and cholesterol acts as a primary staging area for selecting raft proteins. Tailoring of the lipid anchors of raft proteins takes place at this site. Assembly of lipid-anchored proteins on a scaffold of sphingolipids with asymmetric hydrocarbon chains and phospholipids arranged in a quasi-crystalline bilayer structure serves to concentrate and orient the proteins in a manner that couples them functionally within the membrane. Specificity is inherent in the quasi-crystalline lipid structure of liquid-ordered matrices formed by both types of complex into which protein lipid anchors are interpolated. An interaction between the sugar residues of the glycolipids and the raft proteins provides an additional level of specificity that distinguishes one raft from another.
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Affiliation(s)
- Peter J Quinn
- Biochemistry Department, King's College London, 150 Stamford Street, London, UK.
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32
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Jen A, Parkyn CJ, Mootoosamy RC, Ford MJ, Warley A, Liu Q, Bu G, Baskakov IV, Moestrup S, McGuinness L, Emptage N, Morris RJ. Neuronal low-density lipoprotein receptor-related protein 1 binds and endocytoses prion fibrils via receptor cluster 4. J Cell Sci 2010; 123:246-55. [PMID: 20048341 DOI: 10.1242/jcs.058099] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
For infectious prion protein (designated PrP(Sc)) to act as a template to convert normal cellular protein (PrP(C)) to its distinctive pathogenic conformation, the two forms of prion protein (PrP) must interact closely. The neuronal receptor that rapidly endocytoses PrP(C) is the low-density lipoprotein receptor-related protein 1 (LRP1). We show here that on sensory neurons LRP1 is also the receptor that binds and rapidly endocytoses smaller oligomeric forms of infectious prion fibrils, and recombinant PrP fibrils. Although LRP1 binds two molecules of most ligands independently to its receptor clusters 2 and 4, PrP(C) and PrP(Sc) fibrils bind only to receptor cluster 4. PrP(Sc) fibrils out-compete PrP(C) for internalization. When endocytosed, PrP(Sc) fibrils are routed to lysosomes, rather than recycled to the cell surface with PrP(C). Thus, although LRP1 binds both forms of PrP, it traffics them to separate fates within sensory neurons. The binding of both to ligand cluster 4 should enable genetic modification of PrP binding without disrupting other roles of LRP1 essential to neuronal viability and function, thereby enabling in vivo analysis of the role of this interaction in controlling both prion and LRP1 biology.
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Affiliation(s)
- Angela Jen
- Wolfson Centre for Age Related Disease, King's College London, SE1 1UL, UK
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33
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Current Opinion in Clinical Nutrition and Metabolic Care. Current world literature. Curr Opin Clin Nutr Metab Care 2010; 13:215-21. [PMID: 20145440 DOI: 10.1097/mco.0b013e32833643b4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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34
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Staneva G, Chachaty C, Wolf C, Quinn PJ. Comparison of the liquid-ordered bilayer phases containing cholesterol or 7-dehydrocholesterol in modeling Smith-Lemli-Opitz syndrome. J Lipid Res 2010; 51:1810-22. [PMID: 20147702 DOI: 10.1194/jlr.m003467] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The phase behavior of egg sphingomyelin (ESM) mixtures with cholesterol or 7-dehydrocholesterol (7-DHC) has been investigated by independent methods: fluorescence microscopy, X-ray diffraction, and electron spin resonance spectroscopy. In giant vesicles, cholesterol-enriched domains appeared as large and clearly delineated domains assigned to a liquid-ordered (Lo) phase. The domains containing 7-DHC were smaller and had more diffuse boundaries. Separation of a gel phase assigned by X-ray examination to pure sphingomyelin domains coexisting with sterol-enriched domains was observed at temperatures less than 38 degrees C in binary mixtures containing 10-mol% sterol. At higher sterol concentrations, the coexistence of liquid-ordered and liquid-disordered phases was evidenced in the temperature range 20 degrees -50 degrees C. Calculated electron density profiles indicated the location of 7-DHC was more loosely defined than cholesterol, which is localized precisely at a particular depth along the bilayer normal. ESR spectra of spin-labeled fatty acid partitioned in the liquid-ordered component showed a similar, high degree of order for both sterols in the center of the bilayer, but it was higher in the coexisting disordered phase for 7-DHC. The differences detected in the models of the lipid membrane matrix are said to initiate the deleterious consequences of the Smith-Lemli-Opitz syndrome.
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Affiliation(s)
- Galya Staneva
- Institute of Biophysics, Bulgarian Academy of Sciences, Sofia, Bulgaria.
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35
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Lingwood CA, Manis A, Mahfoud R, Khan F, Binnington B, Mylvaganam M. New aspects of the regulation of glycosphingolipid receptor function. Chem Phys Lipids 2010; 163:27-35. [DOI: 10.1016/j.chemphyslip.2009.09.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Revised: 09/15/2009] [Accepted: 09/16/2009] [Indexed: 12/19/2022]
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36
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Morris RJ. Ionic control of the metastable inner leaflet of the plasma membrane: Fusions natural and artefactual. FEBS Lett 2009; 584:1665-9. [PMID: 19913542 DOI: 10.1016/j.febslet.2009.11.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Revised: 11/02/2009] [Accepted: 11/07/2009] [Indexed: 10/20/2022]
Abstract
The phospholipids of the inner and outer leaflets of the plasma membrane face chemically very different environments, and are specialized to serve different needs. While lipids of the outer leaflet are inherently stable in a lamellar (bilayer) phase, the main lipid of the inner layer, phosphatidylethanolamine (PE), does not form a lamellar phase unless evenly mixed with phosphatidylserine (PS(-)). This mixture can be readily perturbed by factors that include an influx of Ca(2+) that chelates the negatively charged PS(-), thereby destabilizing PE. The implications of this metastability of the inner leaflet for vesicular trafficking, and experimentally for the isolation of detergent-resistant membrane domains (DRMs) at physiological temperature, are considered.
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Affiliation(s)
- Roger J Morris
- Wolfson Centre for Age-Related Disease, Guy's Campus, King's College London, UK.
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Thermotropic and structural evaluation of the interaction of natural sphingomyelins with cholesterol. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:1877-89. [DOI: 10.1016/j.bbamem.2009.07.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2009] [Revised: 06/24/2009] [Accepted: 07/08/2009] [Indexed: 11/23/2022]
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38
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Knorr R, Karacsonyi C, Lindner R. Endocytosis of MHC molecules by distinct membrane rafts. J Cell Sci 2009; 122:1584-94. [PMID: 19383725 DOI: 10.1242/jcs.039727] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
In B-lymphocytes, endocytosis of MHC I and MHC II molecules is important for the cross-priming and presentation of labile antigens, respectively. Here, we report that MHC I and MHC II were internalized by separate endocytic carriers that lacked transferrin receptor. Cholera toxin B was co-internalized with MHC II, but not with MHC I, suggesting that the CLIC/GEEC pathway is involved in the uptake of MHC II. Endocytosis of MHC I and MHC II was inhibited by filipin, but only MHC II showed a strong preference for a membrane raft environment in a co-clustering analysis with G(M)1. By using a novel method for the extraction of detergent-resistant membranes (DRMs), we observed that MHC I and MHC II associate with two distinct types of DRMs. These differ in density, protein content, lipid composition, and ultrastructure. The results of cell surface biotinylation and subsequent DRM isolation show that precursors for both DRMs coexist in the plasma membrane. Moreover, clustering of MHC proteins at the cell surface resulted in shifts of the respective DRMs, revealing proximity-induced changes in the membrane environment. Our results suggest that the preference of MHC I and MHC II for distinct membrane rafts directs them to different cellular entry points.
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Affiliation(s)
- Ruth Knorr
- Department of Cell Biology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
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39
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Chen X, Jayne Lawrence M, Barlow DJ, Morris RJ, Heenan RK, Quinn PJ. The structure of detergent-resistant membrane vesicles from rat brain cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1788:477-83. [PMID: 19118517 DOI: 10.1016/j.bbamem.2008.11.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2008] [Revised: 11/20/2008] [Accepted: 11/25/2008] [Indexed: 11/19/2022]
Abstract
The size and the bilayer thickness of detergent-resistant membranes isolated from rat brain neuronal membranes using Triton X-100 or Brij 96 in buffers with or without the cations, K+/Mg2+ at a temperature of either 4 degrees C or 37 degrees C were determined by dynamic light scattering and small-angle neutron scattering. Regardless of the precise conditions used, isolated membrane preparations consisted of vesicles of approximately 100 to 200 nm diameter as determined by dynamic light scattering methods, equating to an area of the lipid based membrane microdomain size of 200 to 400 nm diameter. By means of small angle neutron scattering it was established that the average thickness of the bilayers of the complete population of detergent-resistant membranes was similar to that of the parental membrane at between 4.6 and 5.0 nm. Detergent-resistant membranes prepared using buffers containing K+/Mg2+ uniquely formed unilamellar vesicles while membranes prepared in the absence of K+/Mg2+ formed a mixture of uni- and oligolamellar structures indicating that the arrangement of the membrane differs from that observed in the presence of cations. Furthermore, the detergent-resistant membranes prepared at 37 degrees C were slightly thicker than those prepared at 4 degrees C, consistent with the presence of a greater proportion of lipids with longer, more saturated fatty acid chains associated with the Lo (liquid-ordered) phase. It was concluded that the preparation of detergent-resistant membranes at 37 degrees C using buffer containing cations abundant in the cytoplasm might more accurately reflect the composition of lipid rafts present in the plasma membrane under physiological conditions.
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Affiliation(s)
- Xi Chen
- Pharmaceutical Science Division, King's College London, 150 Stamford Street, London SE1 9NH, UK
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40
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Persaud-Sawin DA, Lightcap S, Harry GJ. Isolation of rafts from mouse brain tissue by a detergent-free method. J Lipid Res 2008; 50:759-67. [PMID: 19060326 DOI: 10.1194/jlr.d800037-jlr200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Membrane rafts are rich in cholesterol and sphingolipids and have specific proteins associated with them. Due to their small size, their identification and isolation have proved to be problematic. Their insolubility in nonionic detergents, such as Triton-X 100, at 4 degrees C has been the most common means of isolation. However, detergent presence can produce artifacts or interfere with ganglioside distribution. The direction is therefore toward the use of detergent-free protocols. We report an optimized method of raft isolation from lipid-rich brain tissue using a detergent-free method. We compared this to Triton-X 100-based isolation along sucrose or Optiprep gradients using the following endpoints: low protein content, high cholesterol content, presence of Flotillin 1 (Flot1), and absence of transferrin receptor (TfR) proteins. These criteria were met in raft fractions isolated in a detergent-free buffer along a sucrose gradient of 5%/35%/42.5%. The use of optiprep gave less consistent results with respect to protein distribution. We demonstrate that clean raft fractions with minimal myelin contamination can be reproducibly obtained in the top three low-density fractions along a sucrose step gradient.
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Affiliation(s)
- Dixie-Ann Persaud-Sawin
- Laboratory of Molecular Toxicology/Neurotoxicology Group, National Institute of Environmental Health Sciences, RTP, NC 27709, USA.
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